At present, there are many wireless communication network operators, who are only granted the right to operate the wireless communication network other than the mobile network. In some strictly restricted areas, terminals cannot roam beyond the area of the cell or of the coverage of single base station or multi base stations that are covered by this wireless communication network. If a terminal roams beyond the coverage, the service could not be provided for this terminal. This is called roam restriction on a terminal.
At present, the method for implementing roam restriction on a terminal could be roughly described as the following: a wireless communication network is divided into many cells and each cell thereof is identified by a number segment. When a terminal on the wireless communication network side subscribes for the permission to roam in a certain cell, the network side will allocate to the terminal International Mobile Subscriber Identity (IMSI) or Mobile Identity Number (MIN) with the number segment corresponding to this cell; when the subscribed terminal starts a call to wireless communication network side or is called, the IMSI/MIN of this terminal will be provided to the wireless communication network side. According to the number segment carried in the terminal's IMSI/MIN, the wireless communication network side can determine the cells the terminal is allowed to roam and further determines whether the roam restriction should be performed on this terminal according to the current cell where the terminal is located, if yes, the wireless communication network side will reject current calling service or being called service; otherwise, the wireless communication network side will process current calling service or being called service.
The method for implementing roam restriction on a terminal has the following disadvantages:
1. due to network optimization, capacity expansion or migration of wireless communication network, the number of the cells will be increased or changed, accordingly it is inevitable to make modification on the wireless communication network side to the relationship between the associated number segments and the cells, for the circumstance of migration, it is also needed to modify the IMSI/MIN of the associated terminals. However, such modification performed one by one is troublesome and is not suitable for commercial applications;
2. a terminal, which is located in the overlapped area covered by both cells, may not be able to start a call or be called. This is because one of the two cells restricts the terminal from roaming in this area, while the other cell allows the terminal to roam. In this case, the terminal will probably receive the calling signal from the roam-restricted cell during a period of time, consequently the terminal cannot call or be called.